I was psyched to hear you guys talk about the last part of this story because Brand New Day has been, as you say, reeeally good and these 2 issues may have been my favorite so far.
Bachalo's art (and I'm pretty sure it's pronounced "ba-CHELL-oh" like the musical instrument or, if you will, "rhymes with JELL-O") is certainly stylized, so it takes some getting used to but so does Darwyn Cooke or Humberto Ramos or any of a number of other guys who work outside the photo-realistic style. I agree that it's a bit of a departure from McNiven and some of the other guys working on this title that do work in that style but the world needs variety and I think this is some of Bachalo's best work - a big improvement from his X-Men stuff which I agree was tough to follow at times.
I also liked the idea of Mayan "villains" (or are they) protecting an ancient mathematical algorithm. I'm a sucker for Mayans and it proves that even after 50+ years and 500+ issues you can still grab a concept right out of real-world history and tell fresh, new story.
But what I liked best about these issues is that it connected Amazing Spidey to Avengers Spidey which I think was needed. I'm not by any means a continuity fanatic but when you're reading both books you can't help but think, "Why doesn't he just ask Danny Rand for some cash?" or, "Shouldn't you be more worried about Skrulls". I don't need to have everything explained in detail but I do like when they acknowledge some type of overarching continuity. So showing Spidey eat Fruity Hoops with Logan in the New Avengers hideout threw me enough of a bone to satisfy the continuity geek in me. Sure it's a shameless Wolverine crossover, but it was a legit, continuity-driven crossover that gave us a time-stamp and filled in some holes. Plus, there's a reason that Wolverine's in 30 book a month. That reason is that he's awesome ... and so was ASM 555 & 556!
Story: 4 - Very Good
Art: 3 - Good